FritzS
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Post by FritzS on Nov 18, 2010 10:41:50 GMT
But I must use two transformers too - transformers with 4 secondary windings are rare ....
Did you use/recommand transformers with EI ore toroidal core?
I must look around for the other parts - the most important is a suitable case.
I will make a DC fault-protection (only on a prototype PCB) too - could you recommend me good relay's for this - that have no influence on sound? I think the current is not the problem.
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Post by Deleted on Nov 18, 2010 10:53:55 GMT
Friedrich
It will work very well with just a single outboard 18-0-18VAC 30VA toroidal transformer. Dual transformers will make a small audible improvement according to Will. I haven't done that yet.
Channel separation already greatly exceeds most other HAs, and may even take a little while to get used to.
Alex
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FritzS
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Post by FritzS on Nov 18, 2010 11:38:21 GMT
I think the using of two separate PSU's needs two separate 18-0-18VAC windings too!?  |
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Post by Deleted on Nov 18, 2010 12:20:03 GMT
I think the using of two separate PSU's needs two separate 18-0-18VAC windings too!? Friedrich As long as the transformer is properly rated there are no problems. I get great results in the SC DAC with 2 PSU PCBs and a paralleled AC input also. 2 transformers will give a minor improvement, but at the cost of a larger external PSU case and transformer, separate primary fuses etc., as well as 2 3 wire connecting leads and associated plugs and sockets for both ends. Alex |
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Will
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Post by Will on Nov 18, 2010 12:28:35 GMT
Just for info, I'll be busy most of this weekend, so have decided that the deadline for the PCB order will be the 26th November. I'll post a final price and details of who to pay etc soon after, and we can get the boards on the way  |
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FritzS
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Post by FritzS on Nov 18, 2010 12:34:41 GMT
Alex, the only little problem I see is the right grounding line  This DC fault-protection suggest me - without the splitter it must work modified - but which relay? This following relays are recommend from AMB Omron G5V-2-H1-DC12 Omron G6A-234P-ST15-US-DC12 or G6A-274P-ST15-US-DC12 Fujitsu RY-12W-K Fujitsu RA-12W-K Tyco C93402 www.amb.org/audio/epsilon12/www.amb.org/audio/epsilon12/epsilon12_120_sch.png |
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Post by Deleted on Nov 18, 2010 13:22:35 GMT
Hi Will
I'll take two sets please.
Syd
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Will
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Post by Will on Nov 18, 2010 13:54:45 GMT
Freidrich, have good read of the e12 instruction page. It's not very clear, but you only connect the PCB to the +/- supply rails of the amp, and not the GND. This is because the e12 has it's own virtual ground.
The only audio signals that you feed into the e12 are the left and right channel outputs, which then go out to the headphone jack. Signal GND bypasses the e12 and goes straight to the headphone socket.
The connection details you want are for 2 channel (passive ground)
Hope this helps,
Will
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Post by Will on Nov 18, 2010 21:46:11 GMT
Here's the list of components, as a handy .xls with clicky links for the parts!
Obviously, I've not put links for the resistors, and things like the electrolytic's are as an example, please fit what you would like. Use the suggested part to get an idea of component size, lead pitch etc. Remember to order a few of each transistor type, so that you can match the parts on both boards, i.e. the BC337, 327, 547 etc on each PCB should have a similar hFE. Take the same care with all the components (diodes, resistors, zener) and you'll end up with a high quality build.
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Post by Will on Nov 18, 2010 22:18:55 GMT
Same again as a .doc.
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Post by Deleted on Nov 18, 2010 23:07:00 GMT
These docs are great Will. Thanks for all your efforts!
Syd
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Post by Deleted on Nov 18, 2010 23:11:18 GMT
I'd be keen to get a set or two Will. Hope there's enough interest.
Syd
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Post by Deleted on Nov 18, 2010 23:17:46 GMT
These docs are great Will. Thanks for all your efforts! Syd X2, the xls doc is perfect! Cheers Will, Chris |
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XTRProf
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Post by XTRProf on Nov 19, 2010 2:19:30 GMT
This amp is just 15W class A and unless we have something like at least 90db/W speaker efficiency, it's better we use it as a HA. I like 15W driving a can in the same mentality of the American spirit. Speaker amps should have at least 100W high current (if SS) or more to control the speakers properly.
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Post by Deleted on Nov 19, 2010 3:13:16 GMT
This amp is just 15W class A and unless we have something like at least 90db/W speaker efficiency, it's better we use it as a HA. I like 15W driving a can in the same mentality of the American spirit. Speaker amps should have at least 100W high current (if SS) or more to control the speakers properly. Chong That is utter garbage ! My DCM QED speakers are 87dB /1W @ 1M I have never been able to use full power from my Class A 15W/Ch amplifier at any house that I have lived in without them being excessively loud. Even then, when I played ""Neil Diamond-Forever in Blue Jeans" in a unit I once lived in , at far less than maximum volume during a thunderstorm, a nearby neighbour complained to the Estate Agent about it. I woke up their baby ! The amplifier was NOT clipping either !!! Many amplifiers don't sound so great at levels well below their maximum power. Of course, if you hold large parties you may want more powerful amplifiers and speakers to drown out the ambient noise!  A very clean sounding amplifier does not normally need to be used at levels of more than a couple of watts unless you live in a big mansion , and how many members would that apply to these days ? Alex |
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Post by Deleted on Nov 19, 2010 6:12:47 GMT
I made REALLY fast peak level detectors that can even detect peaks of a half sinewave at 100kHz.
In normal to pretty loud listening sessions you hardly get past 10W.
to go twice as loud (to the human hearing) you will need 100W, to do that again 1000W.
Must admit that when very short clips are present normal speakers won't even make it noticeable (planars will)
When demoing with high dynamic range recordings (such as la Folia) where the average levels are WAY below the peaks and listening at above average levels my 250W amp sometimes clipped.
At 'normal' listening levels amps rarely pump out more then 1W !
Both you guys have their points...
Take note that most headphones may not receive more then 0.1 to 0.2W (that's why the added output resistors are there for)
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XTRProf
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Post by XTRProf on Nov 19, 2010 6:31:11 GMT
This amp is just 15W class A and unless we have something like at least 90db/W speaker efficiency, it's better we use it as a HA. I like 15W driving a can in the same mentality of the American spirit. Speaker amps should have at least 100W high current (if SS) or more to control the speakers properly. Chong That is utter garbage ! My DCM QED speakers are 87dB /1W @ 1M I have never been able to use full power from my Class A 15W/Ch amplifier at any house that I have lived in without them being excessively loud. Even then, when I played ""Neil Diamond-Forever in Blue Jeans" in a unit I once lived in , at far less than maximum volume during a thunderstorm, a nearby neighbour complained to the Estate Agent about it. I woke up their baby ! The amplifier was NOT clipping either !!! Many amplifiers don't sound so great at levels well below their maximum power. Of course, if you hold large parties you may want more powerful amplifiers and speakers to drown out the ambient noise! A very clean sounding amplifier does not normally need to be used at levels of more than a couple of watts unless you live in a big mansion , and how many members would that apply to these days ? Alex I also have a 86 db/W Wharfedale speaker and my Sonic Impact amps (mono to biamp vertically) at about 14 watts total each channel ran out of steam. I like the American spirit of going flat out, although that could be wasteful, like most of their giant amps and now followed by the British like MF KWatters, to keep the signal as pure and free from distortion and strain as possible. I understand that's overdoing things technically. But it's always better to overdo things in Hifi than underdo or just enough for best sound quality. Also, it always sound better when overdoing things than lesser when we are talking of the last ounce of refinement. That's why I'm more interested in your Class A 15 watter for HP use than the SCHA. Heh, heh, heh ..........  If by theory, we will just need a 0.1 to 0.2 W as expounded by Fran for HP. At that wattage we might as well use OP amps, with the technically better specs than discrete. But better sound subjectively? I don't think so and so do you and us.  |
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Post by Deleted on Nov 19, 2010 6:33:56 GMT
I had peak level LED meters on an earlier amplifier, and that is what I found too.
Previously I had 2 100W/Ch amplifiers, and a 240W/Ch 8 ohm FET Power amplifier. You could always have a high performance low powered Class A amplifier for normal use , where it would be more than adequate, and a lesser quality 100W/Ch amplifier for when you are willing to risk the neighbours calling the Police for a noise complaint.
Times have changed , as far as what are acceptable noise levels these days, and how late at night you are legally permitted to do so .( At least in Australia)
BTW, the 15W Class A is capable of 30W into 4 ohms, albeit not all in Class A, with suitable power supplies and adequate heat sinking..
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XTRProf
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Post by XTRProf on Nov 19, 2010 6:55:17 GMT
I had peak level LED meters on an earlier amplifier, and that is what I found too. Previously I had 2 100W/Ch amplifiers, and a 240W/Ch 8 ohm FET Power amplifier. You could always have a high performance low powered Class A amplifier for normal use , where it would be more than adequate, and a lesser quality 100W/Ch amplifier for when you are willing to risk the neighbours calling the Police for a noise complaint. Times have changed , as far as what are acceptable noise levels these days, and how late at night you are legally permitted to do so .( At least in Australia) BTW, the 15W Class A is capable of 30W into 4 ohms, albeit not all in Class A, with suitable power supplies and adequate heat sinking.. Oh, nowadays we are also talking of Class A 100 Watter and higher as well for crazy people like us, whom we called ourselves audiophiles. Not necessarily for the loudest sound and to warm ourselves during winter but for the highest quality sound. Your Class A 15 Watter, will be super sufficient at > 8ohms as most HPs are not expected to be lower than 8 ohms unless we are going to see the like of the ribbon HPs. I don't see a need for a HA > 15 watts. Of course, there will be those super nuts who say they do. But definitely not me as I don't regard myself as a super nut but a nut. |
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Will
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Post by Will on Nov 19, 2010 7:06:42 GMT
For a bit a clarity, the pcb that's being offered is not the 15W speaker amp. With the components indicated in the cct. on page 4, and listed in the BOM, this amp is suitable for headphone and pre-amp use. (Is the output 2W? 100mA on bias, 20V rails? I've only just woke up!)
The 15W Class A is a 'probably' project for next year, with two people interested so far.
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Post by XTRProf on Nov 19, 2010 7:13:02 GMT
For a bit a clarity, the pcb that's being offered is not the 15W speaker amp. With the components indicated in the cct. on page 4, and listed in the BOM, this amp is suitable for headphone and pre-amp use. (Is the output 2W? 100mA on bias, 20V rails? I've only just woke up!) The 15W Class A is a 'probably' project for next year, with two people interested so far. Oh dear, I wanted that 15 watter as a HA.  Anyway, still ok for what you had done so far as it's a class A amp. I will still support after all the work. Anyway, what's the difference between the topology fo the 2W and the 15 Watter? If about the same but just changes to higher capacity component, might as well modify it as I think more will be interested in 15 watter as a HA as no matter what HPs are thrown at it, the 15 watter will still produce. One of them for the 15 watter as a HA will be me. So Will please take note. Thanks. Got to go now to "do some work" to show the people around that I'm still working. Bye, bye ............. |
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Post by Deleted on Nov 19, 2010 7:18:35 GMT
For a bit a clarity, the pcb that's being offered is not the 15W speaker amp. With the components indicated in the cct. on page 4, and listed in the BOM, this amp is suitable for headphone and pre-amp use. (Is the output 2W? 100mA on bias, 20V rails? I've only just woke up!) The 15W Class A is a 'probably' project for next year, with two people interested so far. Oh dear, I wanted that 15 watter as a HA. Anyway, still ok for what you had done so far as it's a class A amp. I will still support after all the work. One of them for the 15 watter as a HA will be me. So Will please take note. Thanks. Got to go now to "do some work" to show the people around that I'm still working. Bye, bye ............. Chong Even the Class A HA is capable of driving headphones such as the 800s to almost destructive levels due to it's >100mA bias. Alex |
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Post by XTRProf on Nov 19, 2010 7:22:11 GMT
Oh dear, I wanted that 15 watter as a HA. Anyway, still ok for what you had done so far as it's a class A amp. I will still support after all the work. One of them for the 15 watter as a HA will be me. So Will please take note. Thanks. Got to go now to "do some work" to show the people around that I'm still working. Bye, bye ............. Chong Even the Class A HA is capable of driving headphones such as the 800s to almost destructive levels due to it's >100mA bias. Alex Ok, no problem. Like I had said earlier, I still support on this. But I prefer the 15 watter than the 2 watter. Fyi. Really need to go. Ta, ta ........... |
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Post by Deleted on Nov 19, 2010 7:31:37 GMT
Chong Even the Class A HA is capable of driving headphones such as the 800s to almost destructive levels due to it's >100mA bias. Alex Ok, no problem. Like I had said earlier, I still support on this. But I prefer the 15 watter than the 2 watter. Fyi. Really need to go. Ta, ta ........... BTW, there is nothing to stop you increasing the size of the heatsinks on the 2SC5171 and 2SA1930 and further increasing the bias. |
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Post by Deleted on Nov 19, 2010 7:52:42 GMT
O.K. here I go again. a 15W class A amp as intended to drive 15W in class A into 8 Ohm will put out 11Vrms which is 31V peakpeak. This same amplifier that puts out 15W into 8 Ohm when connected to a HD800, which is 300 Ohm, will give ONLY 0.4W (clipping level) and NOT 15 W. This 0.4W is the absolute maximum power without the needed 120 Ohm output resistors where the HD800 is designed to be used with. When these resistors are in place it will drive 0.2W (26 mA) maximum into this headphone. The HD800 is specified to 0.5W so the 15W class A will NOT be able to drive it to it's maximum rating anyway. a class A current of 50 mA will already be MORE then adequate for this particular headphone (NOT for lower Ohmic headphones which will need higher class-A currents.) To drive the HD800 to 0.5W WITH a 120 Ohm series resistor you will need an amplifier that can produce 17V (so needs a supply rails of minimal +/- 25V) in full class A this would need a minimal current of 60 mA. The heat dissipated by such an amp would be 3W per channel which isn't a lot at all. When this amp would also be able to drive full class A into 8 Ohm the amplifier you will need is 37 Watts. It would have an idle current of 3A and will be dissipating 150 Watts of heat. The HD800 will be putting out an ear shattering 124dB (theoretically) Funny thing is.. using a 40W class AB amplifier with an idle current of 50-70mA, which most will have, fitted with a 120 Ohm series resistor, will drive an HD800 to it's maximum level in full class A ! So yes... 2W is MORE the adequate to drive headphones. IF you would pump 2W into the HD800, if it would react linear at this levels, which it doesn't AND the voicecoils would able to handle that power it would be putting out 130dB.  I bet your ears won't like these levels !!! So this is what's needed... only a few Watts BUT with a high voltage. and yes Alex is right the A HA and Panda will be driving an HD800 in full class A without any problems. Hope this clarifies some...  |
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If by theory, we will just need a 0.1 to 0.2 W as expounded by Fran for HP. 
Anyway, still ok for what you had done so far as it's a class A amp. I will still support after all the work. Anyway, what's the difference between the topology fo the 2W and the 15 Watter? If about the same but just changes to higher capacity component, might as well modify it as I think more will be interested in 15 watter as a HA as no matter what HPs are thrown at it, the 15 watter will still produce. One of them for the 15 watter as a HA will be me. So Will please take note. Thanks.
